Semiconductor device having damascene interconnection structure that prevents void formation between interconnections

ABSTRACT

A semiconductor device includes a first insulating layer having a through hole; a first interconnection having a first conductive layer, a first barrier layer, and a first main interconnection; and a second interconnection connected to one of the first conductive layer and the first barrier layer. Accordingly, a problem wherein copper in the first main interconnection transfers from a connection portion thereof to the second interconnection due to electromigration, so that a void is formed at the connected portion resulting in the first interconnection being disconnected from the second interconnection, can be prevented.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of application Ser. No. 10/127,599,filed Apr. 23, 2002, now U.S. Pat. No. 6,759,747 which is a continuationapplication of application Ser. No. 09/329,249, filed Jun. 10, 1999, nowU.S. Pat. No. 6,400,031, which are hereby incorporated by reference intheir entirety for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a semiconductor substrate,and more particularly, the present invention relates to a damasceneinterconnection structure.

This application is a counterpart of Japanese application Serial Number163304/1998, filed Jun. 11, 1998, the subject matter of which isincorporated herein by reference.

2. Description of the Related Art

In general, it is difficult to form a pattern by etching a Copper (Cu)interconnection. In a formation of the Cu interconnection, an insulatinglayer such as SiO₂ or BPSG is formed on a semiconductor substrate. Then,a recess is formed in the insulating layer so as to shape the Cuinterconnection. Then, Cu is buried in the recess. As a result, the Cuinterconnection buried in the recess is a so-called damasceneinterconnection, which is formed on the semiconductor substrate.

Such a damascene interconnection is formed as shown in FIG. 1A-FIG. 1D.FIG. 1A-FIG. 1D are cross sectional views showing a damasceneinterconnection structure of a conventional art.

A first interconnection pattern recess is formed using photolithographytechnique and etching technique in a first SiO₂ film 12 having athickness of 1 μm on the semiconductor substrate 10. Then, a barrierlayer 16 such as a TiN is formed on the first SiO₂ film 12 in the firstinterconnection pattern recess. Then Cu is formed on the entire surfaceand the Cu is polished with alkaline solution having a colloidal-silica,so called CMP (chemical mechanical polishing) method. As a result, afirst interconnection including a main interconnection 19 which is madeup of the Cu, as shown in FIG. 1A. A second SiO2 film 22 having athickness of 1 μm is formed on the first SiO2 film 12 where the firstinterconnection 18 was formed. Then, a through hole 55 is formed in thesecond SiO2 film 22 so that a center portion of an upper surface of thefirst interconnection 18 is exposed, as shown in FIG. 1B.

A second interconnection pattern recess 24 is formed so that apredetermined portion of the through hole 55 is remained. Then, abarrier layer 26 such as TiN is formed in the remained through hole 55and the second interconnection pattern recess 24, as shown in FIG. 1C.

Then, Cu is formed on the entire surface using sputtering technique, andthe Cu is polished using the CMP method. As a result, a secondinterconnection 28 including a main interconnection 29 which is made upof the Cu, as shown in FIG. 1D.

In the conventional art of the method for forming the interconnections,it is desirable to avoid a problem wherein the Cu transfers from aportion connected to the second interconnection due to electromigration,whereby a void is formed at the connected portion, and the firstinterconnection is disconnected from the second interconnection.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductor devicethat can avoid the above noted problem so that the Cu transfers from aportion connected to the second interconnection due to electromigration,whereby a void is formed at the connected portion, and the firstinterconnection is disconnected to the second interconnection.

According to one aspect of the present invention, for achieving theabove object, there is provided a semiconductor device comprising: afirst insulating layer having a through hole; a first interconnectioncomprised a first conductive layer, a first barrier layer, and a firstmain interconnection; the first conductive layer formed on the firstinsulating layer in the first through hole; the first barrier layerformed on the first conductive layer; the first main interconnectionformed on the first barrier layer so as to bury the through hole; and asecond interconnection connected to one of the first conductive layerand the first barrier layer.

According to another aspect of the present invention, for achieving theabove object, there is provided a semiconductor device comprising: afirst insulating layer having a through hole; a first connectioncomprised of a first conductive layer, a first barrier layer, and afirst main interconnection; the first conductive layer formed on thefirst insulating layer in the first through hole; the first barrierlayer formed on the first conductive layer; the first maininterconnection formed on the first barrier layer so as to bury thethrough hole; and a second interconnection connected to one of an edgeportion of the first conductive layer exposed from an upper surface ofthe first insulating layer and an edge portion of the first barrierlayer exposed from an upper surface of the first insulating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter that is regarded as theinvention, the invention, along with the objects, features, andadvantages thereof, will be better understood from the followingdescription taken in connection with the accompanying drawings, inwhich:

FIG. 1A-FIG. 1D are cross-sectional views showing a damasceneinterconnection structure of a conventional art.

FIG. 2 is a plan-view showing a damascene interconnection structureaccording to a first preferred embodiment of a present invention.

FIG. 3 is a cross-sectional view showing damascene interconnectionstructure according to the first preferred embodiment of the presentinvention.

FIGS. 4A-4F are cross-sectional views showing a method for formingdamascene interconnections structure according to the first preferredembodiment of the present invention.

FIGS. 5A-5F are cross-sectional views showing a method for formingdamascene interconnections structure according to the second preferredembodiment of the present invention.

FIG. 6 is a plan-view showing a damascene interconnection structureaccording to a third preferred embodiment of the invention.

FIG. 7 is a cross-sectional view showing a damascene interconnectionstructure according to a third preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A storage device and an alternate processing method for defectivesectors of a storage device according to first and second preferredembodiments of the present invention will hereinafter be described indetail with reference to the accompanying drawings.

FIG. 2 is a plane-view showing a damascene interconnection structureaccording to a first preferred embodiment of a present invention. FIG. 3is a cross-sectional view showing damascene interconnection structureaccording to the first preferred embodiment of the present invention.

As shown in FIG. 2 and FIG. 3, a first damascene interconnectionstructure is preferably made up of a first insulating layer, as a firstSiO₂ 12, having a first through hole, and a first interconnection 18that is buried in the first through hole. The first interconnection 18is preferably made up of a first conductive layer such as a first TiNfilm 16 a, a first barrier layer such as a first Ti film 17 a, and afirst main interconnection 19. The first TiN film 16 a is formed on thefirst SiO₂ 12 in the first through hole. The first Ti film 17 a isformed on the first TiN film 16 a. The first main interconnection isformed on the Ti film 17 a so as to bury the first through hole. Thefirst through hole has a first extending direction and a secondextending direction which is longer than the first extending direction,and is formed so that the second extending direction corresponds to theflow of electrons in the first interconnection 18 which is formed in thefirst through hole.

A second damascene interconnection structure is preferably made up of asecond insulating layer, as a second SiO₂ 22, having a second throughhole, and a second interconnection 28 which is buried in the secondthrough hole. The second interconnection 28 is preferably made up of asecond conductive layer such as a second TiN film 26, a second barrierlayer such as a second Ti film 27, and a second main interconnection 29.The second TiN film 26 is formed on the second SiO₂ 22 in the secondthrough hole. The second Ti film 27 is formed on the second TiN film 26.The second main interconnection 29 is formed on the second Ti film 27 soas to bury the second through hole. The first interconnection 18 isconnected to one of the second TiN film 26 and the second Ti film 27 ofthe second interconnection 28. The second interconnection 28 isconnected to one of the first TiN film 16 a and the first Ti film 17 a.The second interconnection 28 has a protrusion portion where the secondinterconnection 28 is connected to the first interconnection 18. Theprotrusion portion of the second interconnection 28 is connected to thefirst interconnection 18 via the first through hole. In the structurementioned above, when a voltage so as to become a high voltage isapplied to the first interconnection 18 and a voltage so as to become alow voltage is applied to the second interconnection 28, electrons flowfrom the second interconnection 28 to the first interconnection 18. TheCu atoms in the first main interconnection 19 of the firstinterconnection 18 move to opposite direction of electron flow becauseof electomigration. As a result, voids are formed in the first maininterconnection 19 of the first interconnection 18. However, since thesecond interconnection is connected to the first Ti 17 a, the first Ti17 a can maintain electrical connection between the first and secondinterconnections.

FIGS. 4A-4F are cross-sectional views showing a method for formingdamascene interconnections structure according to the first preferredembodiment of the present invention.

As shown in FIG. 4A, a first SiO2 film 12 as a first insulating film, athickness of 1 μm, is formed on a semiconductor substrate 10. Firstinterconnections recesses 14, a depth of 500 nm, are formed in regionswhich first interconnections are formed, using photolithographytechnique and plasma etching with a mixed gas of C2F8 and O2.

As shown in FIG. 4B, TiN films 16, 16 a, a thickness of 30 nm areselectively formed on the first SiO₂ film 12 in the firstinterconnection recesses 14. Ti films 17, 17 a, a thickness of 5 nm, areformed on the TiN films 16, 16 a. CVD (Chemical Vapor Deposition) methodand CMP (Chemical Mechanical Polishing) method are used for forming theTiN films 16, 16 a and the Ti films 17, 17 a. Then, Cu is buried in thefirst interconnection recesses 14 and then is polished until the firstSiO₂ film 12 is exposed, using the CMP method. As a result, a first maininterconnection 19 is formed in the first interconnection recesses 14.Therefore, a first interconnection 18 which is made up of the TiN films16, 16 a, the Ti films 17, 17 a, and the first main interconnection 19,are formed in the first interconnections recesses 14.

As shown in FIG. 4C, a second SiO₂ film as a second insulating film, athickness of 1 μm, is formed on the entire surface. A first through hole50 is formed so as to expose the first SiO₂ film 12 a surface, a portionof the TiN films 16 a, and a portion of the Ti films 17 a in the secondSiO₂ film. A portion of the first SiO₂ film 12 a is removed. As aresult, a portion of the TiN films 16 a sidewalls is exposed. Here, anetching depth is about the half thickness of the first maininterconnection 19.

As shown in FIG. 4D, a second interconnection recess 24, a thickness of500 nm, is formed in the second SiO2 film 22 using plasma etching withC2F8 gas and O2 gas.

As shown in FIG. 4E, a second TiN film 26 and a second Ti film 27 aresuccessively formed on the second SiO2 film in the secondinterconnection recess 24 using the same manner of the forming steps forthe first interconnection 18.

As shown in FIG. 4F, Cu is buried in the second interconnection recess24 using sputtering method or CVD method. After then, the Cu is polisheduntil the second SiO₂ film 22 surface is exposed.

A second interconnection 28 which is made up of the Cu as a second maininterconnection, the second TiN film 26, and the second Ti film 27, areformed in the second interconnection recess 24. Thus, the secondinterconnection 28 is connected to the first TiN film 16 a and the firstTi film 17 a.

FIGS. 5A-5F are cross-sectional views showing a method for formingdamascene interconnection structure according to the second preferredembodiment of the present invention.

As shown in FIG. 5A, a first insulating film 12 is preferably made up ofa SiO2 film 34, a SiN film 32, and a SiO2 film 30. The SiO2 film 34,thickness of 500 nm, is formed on a semiconductor substrate 10. The SiNfilm 32 as etching stop layer, thickness of 50 nm, is formed on the SiO2film 34. The SiO2 film 30, thickness of 500 nm, is formed on the SiNfilm 32.

Then, the SiO2 film 30 is etched using photolithography technique andplasma etching with C2F8 gas and O2 gas. In this time, SiN film 32serves as the etching stop layer against the SiO2 film 30. As a result,the SiO2 film patterns 12 a, 30 and a first interconnection recess 14are formed, respectively.

As shown in FIG. 5B, TiN films 16, 16 a, Ti films 17, 17 a, and firstmain interconnections 19 are respectively formed in the firstinterconnection recess 14 using the same manner for forming steps of thefirst preferred embodiment. Here, a first interconnection 18 is made upof the TiN films 16, 16 a, the Ti films 17, 17 a, and the first maininterconnections 19.

As shown in FIG. 5C, a second insulating film 22 is preferably made upof a SiO2 film 44, a SiN film 42, and a SiO2 film 40. The SiO2 film 44,thickness of 500 nm, is formed on the entire surface. The SiN film 42 asetching stop layer, thickness of 50 nm, is formed on the SiO2 film 44.The SiO2 film 40, thickness of 500 nm, is formed on the SiN film 42.

The SiO₂ film 40 is etched using photolithography technique and plasmaetching with C2F8 gas and O2 gas until the SiN film 42 is exposed. Then,the SiN film 42 is etched using plasma etching with SF6 gas and O2 gas.Then, the SiO₂ films 12, 44 are etched using photolithography techniqueand plasma etching with C2F8 gas and O2 gas until the SiN film 32 isexposed. As a result, a through hole 50 is formed, and a sidewall of theTiN film 16 a, edge of the Ti films 17 a, and a part of the first maininterconnections 19 are exposed in the through hole 50.

As shown in FIG. 5D, a second interconnection recess 24 which is widerthan the through hole 50, is formed by etching the SiO₂ film 40 usingphotolithography technique and plasma etching with C2F8 gas and O2 gas.

As shown in FIG. 5E, a second TiN film 26 and a second Ti film 27 aresuccessively formed in the second interconnection recess 24 and thethrough hole 50 using the same manner of the forming steps for the firstinterconnection 18. Here, before forming the second TiN film 26 and thesecond Ti film 27, another Ti film may be formed in the secondinterconnection recess 24 and the through hole 50. The first maininterconnections 19 are subjected to NH3 used for forming the second TiNfilm 26. As a result, the first main interconnections 19 nitrides, andit is difficult to electrically connect the first interconnection 18 andthe second interconnection 28.

As shown in FIG. 5F, Cu is buried in the second interconnection recess24 using sputtering method or CVD method. Then, the Cu is polished untilthe second SiO₂ film 22 surface is exposed.

A second interconnection 28 which is made up of the Cu as a second maininterconnection, the second TiN film 26, and the second Ti film 27, areformed in the second interconnection recess 24. Thus, the secondinterconnection 28 is connected to the first TiN film 16 a and the firstTi film 17 a.

FIG. 6 is a plan-view showing a damascene interconnection structureaccording to a third preferred embodiment of the invention. FIG. 7 is across-sectional view showing a damascene interconnection structureaccording to a third preferred embodiment of the invention.

As shown in FIG. 6 and FIG. 7, a first interconnection 38 is preferablymade up of a TiN film 16 as a barrier layer, a Ti film 17 as aconductive layer, and a first main interconnection 19 comprising Cu. Thefirst interconnection 38 is formed in a first SiO₂ film 12. A secondinterconnection 48 is preferably made up of a TiN film 26 as a barrierlayer, a Ti film 27 as a conductive layer, and a first maininterconnection 29 comprising Cu.

The second interconnection 48 is formed so as to cover an upper surfaceof and a sidewall of the first interconnection 38.

Since a connecting area is wider than the conventional art, a contactresistance is low and a current flow is easy. Therefore, it can avoidthe electromigration.

In the structure mentioned above, when a voltage so as to become a highvoltage is applied to the first interconnection 38 and a voltage so asto become a low voltage is applied to the second interconnection 48,electrons flow from the second interconnection 48 to the firstinterconnection 38. The Cu atoms in the first main interconnection 19 ofthe first interconnection 38 move in opposite direction of electron flowbecause of electromigration. As a result, voids are formed in the firstmain interconnection 19 of the first interconnection 38. However, sincethe second interconnection 48 is connected to the first Ti 17 a, thefirst Ti 17 a can maintain electrical connection between the first andsecond interconnections.

While the present invention has been described with reference to theillustrative embodiments, this description is not intended to beconstrued in a limiting sense. Various modifications of the illustrativeembodiments, as well as other embodiments of the invention, will beapparent to those skilled in the art on reference to this description.It is therefore contemplated that the appended claims will cover anysuch modifications or embodiments as fall within the true scope of theinvention.

1. A semiconductor device comprising: a first insulating film; a firstinterconnection formed in the first insulating film, the firstinterconnection extending in a first direction and having a first widthin a second direction that is substantially perpendicular with the firstdirection; a second insulating film overlying the first insulating film;and a second interconnection formed in the second insulating film, thesecond interconnection having an interconnection portion having a firstlength in the second direction and a contact portion formed between theinterconnection portion and the first interconnection, the contactportion having a second width in the second direction that is smallerthan the first length and larger than the first width, and being indirect contact with an outer side surface and an upper surface of thefirst interconnection, the interconnection portion having a secondlength in the first direction, and the contact portion having a thirdlength in the first direction that is not greater than the secondlength, wherein the interconnection portion and the contact portion area same material and contiguous with respect to each other without aninterface there between.
 2. A semiconductor device comprising: a firstinsulating film having a first cavity extending in a first direction andhaving a first width in a second direction that is substantiallyperpendicular with the first direction; a first interconnection formedin the first cavity of the first insulating film; a second insulatingfilm overlying the first insulating film, the second insulating filmhaving a second cavity; and a second interconnection formed in thesecond cavity of the second insulating film, the second interconnectionhaving an interconnection portion having a first length in the seconddirection and a contact portion formed between the interconnectionportion and the first interconnection, the contact portion having asecond width in the second direction that is smaller than the firstlength and larger than the first width, and being in direct contact withan outer side surface and an upper surface of the first interconnection,the interconnection portion having a second length in the firstdirection, and the contact portion having a third length in the firstdirection that is not greater than the second length, wherein theinterconnection portion and the contact portion are a same material andcontiguous with respect to each other without an interface therebetween.
 3. A semiconductor device comprising: a first insulating filmhaving a first recess extending in a first direction and having a firstwidth in a second direction that is substantially perpendicular with thefirst direction; a first interconnection formed in the first recess ofthe first insulating film; a second insulating film overlying the firstinsulating film, the second insulating film having a second recess; anda second interconnection formed in the second recess of the secondinsulating film, the second interconnection having an interconnectionportion having a first length in the second direction and a contactportion formed between the interconnection portion and the firstinterconnection, the contact portion having a second width in the seconddirection that is smaller than the first length and larger than thefirst width, and being in direct contact with an outer side surface andan upper surface of the first interconnection, the interconnectionportion having a second length in the first direction, and the contactportion having a third length in the first direction that is not greaterthan the second length, wherein the interconnection portion and thecontact portion are a same material and contiguous with respect to eachother without an interface there between.
 4. A semiconductor devicecomprising: a first insulating film; a first interconnection formed inthe first insulating film, the first interconnection extending in afirst direction and having a first width in a second direction that issubstantially perpendicular with the first direction; a secondinsulating film overlying the first insulating film; and a secondinterconnection formed in the second insulating film, the secondinterconnection having an interconnection portion having a first lengthin the second direction and a contact portion formed between theinterconnection portion and the first interconnection, the contactportion having a second width in the second direction that is smallerthan the first length and larger than the first width, and being indirect contact with an outer side surface and an upper surface of thefirst interconnection, wherein the interconnection portion and thecontact portion are a unified same material and contiguous with respectto each other without an interface there between.
 5. The semiconductordevice according to claim 4, wherein the first insulating film includessilicon oxide.
 6. The semiconductor device according to claim 4, whereinthe second insulating film includes silicon oxide.
 7. The semiconductordevice according to claim 4, wherein the first interconnection includesa first barrier film and a first main interconnection.
 8. Thesemiconductor device according to claim 7, wherein the first barrierfilm includes titanium.
 9. The semiconductor device according to claim7, wherein the first main interconnection includes copper.
 10. Thesemiconductor device according to claim 4, wherein the secondinterconnection includes a second barrier film and a second maininterconnection.
 11. The semiconductor device according to claim 10,wherein the second barrier film includes titanium.
 12. The semiconductordevice according to claim 10, wherein the second main interconnectionincludes copper.
 13. A semiconductor device comprising: a firstinsulating film having a first cavity extending in a first direction andhaving a first width in a second direction that is substantiallyperpendicular with the first direction; a first interconnection formedin the first cavity of the first insulating film; a second insulatingfilm overlying the first insulating film, the second insulating filmhaving a second cavity; and a second interconnection formed in thesecond cavity of the second insulating film, the second interconnectionhaving an interconnection portion having a first length in the seconddirection and a contact portion formed between the interconnectionportion and the first interconnection, the contact portion having asecond width in the second direction that is smaller than the firstlength and larger than the first width, and being in direct contact withan outer side surface and an upper surface of the first interconnection,wherein the interconnection portion and the contact portion are a samematerial and contiguous with respect to each other without an interfacethere between.
 14. The semiconductor device according to claim 13,wherein the first insulating film includes silicon oxide.
 15. Thesemiconductor device according to claim 13, wherein the secondinsulating film includes silicon oxide.
 16. The semiconductor deviceaccording to claim 13, wherein the first interconnection includes afirst barrier film and a first main interconnection.
 17. Thesemiconductor device according to claim 16, wherein the first barrierfilm includes titanium.
 18. The semiconductor device according to claim16, wherein the first main interconnection includes copper.
 19. Thesemiconductor device according to claim 13, wherein the secondinterconnection includes a second barrier film and a second maininterconnection.
 20. The semiconductor device according to claim 19,wherein the second barrier film includes titanium.
 21. The semiconductordevice according to claim 19, wherein the second main interconnectionincludes copper.
 22. A semiconductor device comprising: a firstinsulating film having a first recess extending in a first direction andhaving a first width in a second direction that is substantiallyperpendicular with the first direction; a first interconnection formedin the first recess of the first insulating film; a second insulatingfilm overlying the first insulating film, the second insulating filmhaving a second recess; and a second interconnection formed in thesecond recess of the second insulating film, the second interconnectionhaving an interconnection portion having a first length in the seconddirection and a contact portion formed between the interconnectionportion and the first interconnection, the contact portion having asecond width in the second direction that is smaller than the firstlength and larger than the first width, and being in direct contact withan outer side surface and an upper surface of the first interconnection,wherein the interconnection portion and the contact portion are a samematerial and contiguous with respect to each other without an interfacethere between.
 23. The semiconductor device according to claim 22,wherein the first insulating film includes silicon oxide.
 24. Thesemiconductor device according to claim 22, wherein the secondinsulating film includes silicon oxide.
 25. The semiconductor deviceaccording to claim 22, wherein the first interconnection includes afirst barrier film and a first main interconnection.
 26. Thesemiconductor device according to claim 25, wherein the first barrierfilm includes titanium.
 27. The semiconductor device according to claim25, wherein the first main interconnection includes copper.
 28. Thesemiconductor device according to claim 22, wherein the secondinterconnection includes a second barrier film and a second maininterconnection.
 29. The semiconductor device according to claim 28,wherein the second barrier film includes titanium.
 30. The semiconductordevice according to claim 28, wherein the second main interconnectionincludes copper.